Dry cell and method of manufacturing the same



. w.,.. SCHUHE. DBY CELL AND METHODOF MANUFACTURING THIAS'AMF. 4APPLICATION met MAY fsw; 1929;.v

UNITED STATES PATENT roFFlcE.

WALTER is. sCIIoLTE, or MADISON, wIsCONsIIxI,` AssIGNOR TO BURGEssBATTERY' COMPANY, A CORPORATION or WISCONSIN.

DRY CELL ANnMETIIon OF MANUFACTURING THESAME.

do hereby declare the following to 'be a full,

clear, and exact description ofy the invention, such as will enableothers skilled in the art to which it appertains to make and use thesame. 5

The present invention relates Ato dry cells and particularly to thecathodes of suchv Cells, and to the method by which the cathodes areprovided with a wrapping of bibulous material to prevent the electrodefrom disintegrating into the electrolyte, particularly` during theassembly of the several parts into a complete dry cell.l

It is an object of the present invention to eliminate ,air bubbleswithin the bibulous envelop or between the envelop and the gelatinizedpaste commonly used in dry cells of the sO-called bag` type. f

It is a further object of the invention to eliminate -some of thetedious hand labor incident to the use of'a cheesecloth bag or envelopheld` in place by a wrapping of thread.

Other objects and advantagesof the present invention will be made Aclearvby the following detailed description, which is to be taken inconjunction with the accompanying drawings, wherein Figure 1 is aperspective view of a dry cell cathode constructed in accordance withthe present invention, and Fig. 2 is a sectional elevation through acomplete dryfcell.

In the manufacture of dry cells, ,it is customary to prepare a mixtureor mix of manganese dloxid, such as pyrolusite, together with'carbonaceous material,.su ch as graphite and retort carbon, and'usualsalts and water as explained, for instance, in BurgessU.S.15 ber 30,1915, and then to compress this damp and plastic mixture about a carbonrodlto form al core, or cathode, for the dry call. Thismolding. of theplastic mix into cylin- Specication of Letters Patent. v Applicationl'ed Hay l1li, 19,20. Serial No. 381,653.

atent No. 1,162,449, dated Novem- Patented Mam, 1921;

drical form with a carbon rod in the center may be Adone lin suitableapparatus, as, for instance, inthetamping machine of Hambuechen U. SIPatent No, 1,232,297, dated July 3, 1917. r1"he cathodes so formed,although strong enough for. manipulation on a' factory basis, arenevertheless fragile in character and subject to disintegration, Y

particularly if their moisture content isv changed substantially fromthat at which they are molded. As'they come from the molding machine,ready for wrapping, they are s0,4 soft that it is possible for. theoperatorl easily to crush them between his -thumb and forefinger.

A customary molded cathode Vfrom disintegration during the further'steps in the assembly is to wrap vthelcore with cheesecloth. Thecheesecloth ordinarily used isa fine grade, unsized mater1al, and 1nconformity with usual pracwrapping of thread. The cloth is brought wayofprotecting such a.

A tice, is held in'place around the core with a around the bottom-,ofthe core and over the top, and the thread is wound ',not `only aroundthe perimeter of the core,- but also longitudinally and parallel withthe carbon Y.

pencil. The wrapped core so produced can then'with advantage be dippedvinto a very shallow 'layer of melted paraffin to form an insulatinglayer or film across the bottom, as

explained, for instance, in Burgess U. S.

Patent No. 1,211,363, dated January 2, 1917.

.The cheesecloth is expensive, and the operation, of winding the wrappedcores with thread, being a hand'operation, is tedious and likewiseexpensive.- Also, there is danger that through unskilled handling, the

v soft and plastic' cores will be deformed.

Also some of the activemixmay nd its way to they outside of thecheesecloth wrapping, and on assembly of the dry cell, be washed overinto' contact with the zinc, where it can produce local action withdestructive results.

In conformity with the method of the present invention, the `bibul'ousenvelop or" wrapping for the cathode is held in place, not by windingwith thread, but by means of an adhesive. This method permits thetionable.

" the most suitable is one that is thin but use either of paper or ofcheesecloth as the bibulous material, and there is some economy inlabor. But of more importance than'this is the gain in the quality ofthe 6 dry cell because of the absence of air bubbles within and withoutthe bibulous enl v'elop, as hereinafter explained more at length.

If cheesecloth is to be used as the bibulous 1`0 envelop', it may be Iofthe quality .now commonly used for this purpose. I paper is to be used,as the wrapplng, it should be a od uality,'-thin and porous tissuepaper. slig tly calendered surface is not objec- The adhesive which Ihave found does not settle. A starch ,paste suitable for this work maybe made by adding arrowroot to boiling water to the extent of about20`one per -1 cent. by weight, though other The procedure for applyingthe envelop to the core consists in dippingv each molded core into thearrowroot solution and then, while the core is still wet from theadhesive, Wrapplng it with the drycheesecloth or v paper and foldingdown'the wrapping at both ends of the core to cover its top nd bottom,care being taken to press out any air bubbles and to secureintimateunion between the wrapping andthe sticky surface 10 beneath.This operation calls for some skill and jud ent. The diiliculties are'that the core is iable to an incipient breaking up `when it is dippedinto the adhesive, thereby soiling and lmpairin the adhesive.Furthermore, the coreta es up in its poresan appreciable quantity of theadhesive, therebag type having a bibulous envelop pasted by becomingsofter and morev diicult to manlpulate durin subsequent manufacturlngoperations. fter being wrapped, the

I l cores must be separatedfrom each other in the trays during the' timethat they" are drying, as otherwise they may stick,v to one,

another because of the soaking through of some of the adhesive' held bythe core.

There is a tendency, also, for the carbon to loosen from the core justduring the time that the paste is setting. These dificulties are not,however, serious, and onceappreciated, can be adequately guardedagainst.

After the cores have been wrapped and dried, they can be yintroducedinto their respective zinc cups and a gelatinizable electrolyte can bepoured in to fill the space between the zinc and the bibulous envelop.

Then, after cooking or such other treatment,

\ concurrently herewith, I have described and if any, as is necessary togelatinize-the electrolytic paste, the cell can be nished oii' in usualmanner.

The construction above described is illustrated in the drawing, where 1is the car- 70 formed by dipping the core into a thm layer ofmeltedparain. 7is the zinc electrode or anode, 8 lis thegelatinized-paste, 9 is a par` 80 aHin paper washer, and 10ris a layerof pltch or sealing wax. A

Becausevof the method by which the envelop is applied to the core, noair bubbles need be entrapped between it and the core.

EnoughA of4 the adhesive comes out of the pores of the core to lill thepores of the wrapping, and, consequently, after 'the core has .beenplaced in its zinc cup, and the gelatinizable electrolyte hasv beenintroduced, the electrolyte will wet and make good contact with theouter face` of the" starch-filled envelop, thereby avoiding entrapmentof air on the outer face of the' envelop. The envelop is of uniformelectrical conductivity, and because of the ab sence of. air bubbles,vthe Hash of the bat- The process effectsa saving both of labor andmaterial, and permitsl the tery ishigher.

easy substitution 'of paper for the more yexpensive cheesecloth wrappingno-W commonly used.

It is not readily feasible vmerely to suby stitute paper for cheeseclothand wrap it around with thread, for the paper is. stiif and tears, Vandair bubbles are formed within the envelop which give a low flash to thebattery and otherwiseimpair its quality.

Inmy application Serial No. 381,652,f1led claimed broadly a dry cell'vcathode of the in place, and I have claimed the step which consists inpasting the bibulous envelop to the cathode preparatory to addition ofthe electrolyte.

vI clalmz- '1. A dry-cell ycathode impregnated in part, at least, withan adhesive, and having a bibulous envelop held in place by saidadhesive substantial y as described.

2. A dry-cell cathode impregnated in part, at least, with a starchadhesive, and having a bibulous envelop held in place by said adhesivesubstantially as described.

3. A dry-cell cathode impregnated in part, at least, with a starchadhesive, and 'having a paper envelop held in place by j said adhesive,substantially as described.

4. In the manufacture of dry-cells, the 180 ammat-ically illus- `I5steps which consist in partially impregnating a molded cathode with anadhesive, and then wrapping said cathode with a, bibulous envelop andthus securing said envelop in place, substantially as described. A

5. In the manufacture of dry-cells, the steps which consist in partiallyimpregnating the molded cathode with a starch adhesive, and thenwrapping said cathode with a paper envelop and thus securing said en- 10velop in place, substantially as described.

6. In the manufacture 4of dry-cells, the steps which consist in dippingthe molded cathode in a suitable adhesive, and then wrapping saidcathode in tially as described.

In testimony whereof I aiix m si ature.

WALTER B.SC TE.

paper, substan- 15

